Vanadate(1-), oxo[phosphato(3-)-.kappa.O]-, hydrogen, hydrate (2:2:1)

Endpoint summary

Description of key information

Of the limited effects noted following oral exposure of soluble vanadium substances, it appears most likely that effects on haematological parameters are the most consistently reported among a number of investigators.

Information on repeated dose toxicity following inhalation exposure to divanadium pentaoxide is available in a NTP study (NTP 2002) with exposure of male and female rats and mice to V2O5 over 16-days, 3-months and 2-years. Pulmonary reactivity to divanadium pentaoxide was also investigated following subchronic inhalation exposure in a non-human primate animal model.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

Data of the repeated-dose toxicity via the dermal route are not available for any vanadium substance. Following the HERAG guidance for metals and metal salts (see section 7.1.2 of the technical dossier: dermal absorption), negligible percutaneous uptake based on minimal penetration, i.e. a dermal absorption rate in the range of maximally 0.1 - 1.0 %, can be anticipated. Dermal absorption in this order of magnitude is not considered to be “significant”. Thus, regarding repeated-dose toxicity of vanadium substances, the dermal exposure route is not expected to be the most relevant.
ium substances, the dermal exposure route is not expected to be the most relevant.

References:
EBRC (2007) HERAG fact sheet - Assessment of occupational dermal exposure and dermal absorption for metals and inorganic metal compounds, EBRC Consulting GmbH, Hannover, Germany, August 2007, 49 pages.

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

Data of the repeated-dose toxicity via the dermal route are not available for any vanadium substance. Following the HERAG guidance for metals and metal salts (see section 7.1.2 of the technical dossier: dermal absorption), negligible percutaneous uptake based on minimal penetration, i.e. a dermal absorption rate in the range of maximally 0.1 - 1.0 %, can be anticipated. Dermal absorption in this order of magnitude is not considered to be “significant”. Thus, regarding repeated-dose toxicity of vanadium substances, the dermal exposure route is not expected to be the most relevant. In addition, sodium metavanadate does not have any potential for skin irritation as indicated by the lack of any effects in the respective in vitro skin irritation test.

References:
EBRC (2007) HERAG fact sheet - Assessment of occupational dermal exposure and dermal absorption for metals and inorganic metal compounds, EBRC Consulting GmbH, Hannover, Germany, August 2007, 49 pages.

Additional information

No substance specific data on repeated dose toxicity is available for the registered substance Vanadate(1-), oxo[phosphato(3-)-κO]-, hydrogen, hydrate (2:2:1) is available.

 

Vanadate(1-), oxo[phosphato(3-)-κO]-, hydrogen, hydrate (2:2:1) is a dark-grey powder with a melting point > 400°C and a water solubility of ca. 150 g/L (determination via V: 148 g/L ± 17 g/L and determination via P: 156 g/L ± 16 g/L f or at 20°C). For this compound the oxidation state of V (+4). The chemistry of vanadium and inorganic vanadium substances is complex. However, under physiological conditions only the vanadyl ion (VO²⁺, +4-valent) and the vanadate ion (VO₄^3-, +5-valent) play a significant role. Within tissues of organisms, V(+4) predominate because of largely reducing conditions; in plasma, V(+5) predominates. Under physiological conditions both forms of ions are going to be converted into each other via redox reactions. Therefore, it can be assumed that +4- and +5-valent inorganic vanadium compounds will show the same toxicological profile. Data from soluble +4- and +5-valent vanadium substance were taken into account to address the endpoint of repeated dose toxicity of the registered substance.

Oral - animal data:

Three groups of five male and five female CD rats received E-326 catalyst (Divanadyl pyrophosphate, CAS 65232 -89-5) by oral gavage at dosages of 20, 100 or 500 mg/kg/day for four consecutive weeks. The test material was administered in 1% w/v methylcellulose in distilled water. Rats of the control group received the vehicle alone.

One male rat treated at 500 mg/kg/day died and two female rats treated at the same dosage were killed on humane grounds. The male showed bodyweight loss from Day 15, loose faeces on Day 19 and was found dead on Day 20 of the dosing period. Necropsy findings were unremarkable. Histopathology revealed diminished glycogen and congestion in the liver. One female showed bodyweight loss from the beginning of the study, loose faeces, hunched posture and piloerection on Day 3 and was killed on Day 4. Necropsy revealed enlarged mesenteric lymph nodes, gas-distended stomach and pale kidneys. Histopathology revealed papillary mineralisation in the right kidney, plasmocytosis and parafollicular hyperplasia in the mesenteric lymph nodes and diminished glycogen and congestion in the liver. The remaining female was hunched, thin and had reduced body temperature and muscle tone, muscle tremor, rapid respiration, piloerection and pallor on Day 21, and was killed on the same day. Necropsy revealed slight hydronephrosis in the right kidney and prominent splenic white pulp. Histopathology revealed hydronephrosis and vacuolation or degeneration of the right kidney tubules, hepatocytic degeneration and inflammation, diminished glycogen and congestion in the liver and atrophy of the splenic white pulp.

Occasional salivation at dosing was observed from Day 20 onwards in surviving female rats receiving 500 mg/kg/day. There was also a similar observation on one occasion in one female treated at 100 mg/kg/day. Food consumption and bodyweight gain of females treated at 500 mg/kg/day were slightly inferior to those of the controls. Food utilisation efficiency was considered to have been unaffected. The mean red cell-volumes of rats treated at 500 mg/kg/day were lower than those of the controls. In addition, haemoglobin concentrations and packed cell volumes were slightly lower and red cell numbers slightly higher than those of the controls. Females treated at this dosage had slightly lower lymphocyte and corresponding total leucocyte numbers and slightly higher platelet counts than the female controls. The plasma alanine amino-transferase activities of male and female rats treated at 500 mg/kg/day and female rats treated at 100 mg/kg/day were slightly higher than those of the controls. The plasma urea concentration of male rats treated at 500 mg/kg/day was marginally higher than that of the male controls and the plasma alkaline phosphatase activity of females treated at this dosage was slightly lower than that of the female controls. Urine was considered to have been unaffected by treatment with E-326 catalyst. There were no differences in organ weights between treated and control animals that could be unequivocally attributed to an effect of E-326 catalyst. There was no macropathological or histopathological change which was attributed to treatment with E-326 catalyst.

It is concluded that treatment with E-326 catalyst at a dosage of 500 mg/kg/day for four consecutive weeks caused the death of three rats, disturbance in the formed elements of the blood and minor changes in blood chemistry. Effects at 100 mg/kg/day were essentially confined to a marginal increase in plasma alanine amino-transferase activity in females. There was no microscopic change which was attributed to treatment with E-326 catalyst. The "no-toxic effect" level (NOEAL) of administration was considered to be 100 mg/kg/day and the "no-effect" level (NOEL) was considered to be 20 mg/kg/day.

A number of studies are available where vanadium compounds were administered, however they have involved different experimental approaches and designs as well as different dose regimens, and endpoints. The most consistent effect of exposure to vanadium compounds, i.e. pulmonary irritation and inflammation, is associated with the inhalation route. For oral exposure, effects are more limited and the different experimental approaches lead to a variety of endpoints measured. Of the limited effects noted following oral exposure, it appears most likely that effects on hematological parameters are the most consistently reported among a number of investigators (Mountain et al 1953, Zaporowska et al. 1993, Scibior et al 2006, Scibior, 2005, NTP, 2002).

In a study (treatment of male rats for 103 days) with the focus on reduction of the cysteine content in rat hair (Mountain et al. 1953), reduced erythrocyte counts and levels of hair cysteine were observed dose-dependently at dose levels of 100 and 150 ppm vanadium in the diet. Effects on hair cysteine levels and on red blood cell parameters may correlate with erythropenia and anaemia. Similar haematological effects were observed by Zaporowska et al. (1993) in a 4-week toxicity study. Rats received NH₄VO₃at dose levels of 1.5 and 5-6 mg V/kg bw/d via drinking water.

Haematological examinations showed a decrease in erythrocyte counts (associated with increased reticulocyte counts), haemoglobin and haematocrit levels in both groups. Effects of vanadium and chromium on body weight gain and selected haematological and blood parameters in rats were also investigated by Scibior (2005) following administration of NaVO₃to rats via drinking water for a period of 6 weeks. Treatment of rats with about 8 mg V/kg bw/d resulted in effects on body weight and erythrocytes (increased no. of erythrocytes, haemoglobin, and decrease of MCV, MCH, MCHC and leucocytes).

Altogether, effects noted have included reduced haemoglobin, reduced hematocrit, reduced mean cell haemoglobin concentrations, while effects on red blood cells have included both reductions and increases depending on dose levels used and duration of treatment, perhaps compensating for the hemoglobin effect. Hematological effects have been found with a variety of different vanadium compounds including sodium metavanadate, vanadium pentoxide, and ammonium metavanadate supporting the use of this endpoint.

The fact that evidence of hematological effects was also observed following 90-day inhalation exposure to vanadium pentoxide, in the absence of other remarkable systemic toxicity (NTP, 2002), increases the confidence in this being the appropriate critical effect for oral exposure from the available dataset. Additional support for the reliability of this endpoint comes from a study by Hogan (2000), where haematological effects were demonstrated following IV injection of three different vanadium compounds each with a different valence state (vanadium chloride (V-III); vanadyl sulphate (V-IV); and sodium orthovanadate (V-V)).

Few other signs of systemic toxicity following oral ingestion of vanadium compounds have been reported in other studies, but they do not show a consistent picture. In a study conducted by Domingo et al. (1985), some evidence for renal effects were reported following exposure for 3 months to sodium metavanadate however the effects (increased plasma protein, urea and uric acid) were limited to the top dose with the mid and low dose not being affected. Organ weights, including kidneys, were not affected, and histopathology data were not reported (Domingo et al. (1985). Other studies (Susic and Kentera 1988; NTP 2002) including some assessment of renal function have not shown similar effects although only limited information is available. However, in a study in rats with chronic dietary administration (24 wks) of vanadate (Susic & Kentera, 1988), changes were seen in cardiac output and total peripheral resistance at dose levels of 300 and 3000 ppm NaVO₃in the diet. In addition, there was an effect on hematocrit (increase), plasma and blood volume (decrease) as well as extracellular fluid in the high dose group. In another subchronic study (2 months) by Susic & Kentera (1986), 300 ppm represents an effect level for pulmonary function. In this study, no effects were observed on hematocrit levels. The results of a study reported by Jadhav and Jandhyala (1983) suggest that the cardiovascular system responded to vasoconstrictor agents in a dose-dependent manner after subchronic (6 weeks) oral vanadate exposure (drinking water) favouring the development of high blood pressure.In a subchronic study (8 weeks) on behavioural effects of orally administered NaVO₃in rats, effects on general activity and learning were observed already at the lowest dose level of 4.1 mg/kg bw/d (Sanchez et al. 1998).

Treatment of male rats with different dose levels of vanadyl sulfate in drinking water corresponding to 34, 54 and 90 mg/kg bw/day over 52 weeks did not indicate severe signs of systemic toxicity under the conditions of this study. Body weights were dose-dependently reduced in treatment groups compared to controls, occasionally reaching statistical significance in the low and mid dose groups and at most time points in the high dose group. Based on these effects, the lowest dose level of 34 mg/kg bw/d represents a LOAEL.

Based on the available limited data on repeated dose toxicity following oral exposure of soluble tetra- and pentavalent vanadium substances, effects on red blood cell parameters can be regarded as the most robust effect of systemic toxicity. This is further backed by results from a 90-day NTP study (2002) with inhalation exposure of rats. Of the studies showing hematological effects, several of the studies measured the effect with one dose of vanadium compound while other treatment groups received vanadium combined with other substances. These studies are regarded as supportive. Results from the Mountain et al. study (1953) were selected as the starting point for derivation of the DNEL for oral exposure, because it represents the study with the longest duration (103 days) and included several dosage groups. Although the effects observed at the low dose level of 100 ppm V (178 mg V2O5/kg ) in the diet are only minimal, this dose level is regarded to represent a LOEL in order to protect for potential other toxicological effects. Almost similar results were obtained by Zaporowska et al. (1993) in a 4-week toxicity study, but as the study is only of short-term duration, it is considered as supportive.

Conversion of LOEL (ppm in diet) to LOEL (mg/kg bw /d):

LOEL:             100 ppm V                  Duration:                                 103 d

Food intake:    2,130 g/rat                   Body weight (kg bw/rat):          0.5 kg

V ingested reported:                           155 mg V/rat/103 d= 1.5 mg V/kg

LOEL_corrected= 3.0 mg V/kg bw/d based on exposure to soluble forms ( = 5.36 mg V2O5/kg bw/d)

Inhalation - animal data:

The most informative study is the standard NTP chronic inhalation carcinogenicity study (NTP 2002) using V2O5. In this investigation, there was a statistical increase in lung tumours in mice of both sexes, but not in rats (Starr, 2012).

In mice, survival rates of male mice exposed to 4 mg/m3 was less than that of chamber controls, and mean body weights of male mice exposed to 4 mg/m3 and all exposed groups of female mice were generally less than those of the chamber controls throughout the study. As in the 3-month studies, the respiratory tract was the primary site of toxicity. Under the conditions of this 2-year inhalation study there was evidence of carcinogenic activity of vanadium pentoxide in male and female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms. Exposure to vanadium pentoxide caused a spectrum of non-neoplastic lesions in the respiratory tract (nose, larynx, and lung) including alveolar and bronchiolar epithelial hyperplasia, inflammation, fibrosis, and alveolar histiocytosis of the lung in male and female mice. Hyperplasia of the bronchial lymph node occurred in female mice. The lowest concentration tested (1 mg/m3) represents a LOAEC for local effects in the respiratory tract.

Pulmonary reactivity was investigated in a subchronic inhalation study in cynomolgus monkeys (duration 6 months) with divanadium pentaoxide. The results showed a concentration-dependent impairment in pulmonary function, characterized by airway obstructive changes (pre-exposure challenges) accompanied by a significant influx of inflammatory cells recovered from the lung by bronchoalveolar lavage. Subchronic V2O5 inhalation did not produce an increase in V2O5 reactivity, and cytological, and immunological results indicate the absence of allergic response.

Inhalation - human data:

Regarding the preferential use of human data in risk assessments for human health, a respective statement is attached below.

There are several epidemiological studies linking upper respiratory symptoms to vanadium pentoxide exposure (Kiviluoto, 1980; Kiviluoto et al., 1979a; Lewis, 1959, Zenz and Berg, 1967 Zenz et al. 1962). Long-term chronic exposure data of workers in the vanadium industry are reported in several publications. In a factory manufacturing vanadium pentaoxide, 63 workers exposed to V₂O₅at concentrations of 0.1 to 3.9 mg V/m³measured as total dust for 11 years (average 0.2-0.5 mg V/m³) did not have an increased prevalence of upper respiratory symptoms in the case study by Kiviluoto et al (1979a,b, 1980, 1981a,b).

 Kiviluoto et al. (1979b) did not observe any differences in the anterior and posterior rhinoscopy in the exposed groups after 11 years of exposure to average V₂O₅levels of 0.2-0.5 mg V/m³as listed above. Furthermore, there was no difference in the number of blood vessels between the exposed and non-exposed groups. However, the number of neutrophils in the nasal smears and the number of plasma cells in the nasal mucosa were increased indicative of a protective mechanism in the mucosa. Other examined factors of the biopsies and cell findings did not differ between the exposed workers and the controls. Chest radiographs and lung function tests did not reveal any differences. After further 7-11 months of V₂O₅exposure at concentrations ranging from 0.01 to 0.04 mg V/m³measured as total dust, a subsequent reexamination revealed that the cell findings did not indicate any further significant changes between the studied exposed groups, and that there were no significant changes in the number of eosinophils of cytological and histological samples.

Altogether, no pneumoconiosis and no other signs indicative of allergic inflammation, including nasal catarrh, cough, phlegm, were observed by Kiviluoto et al. in the exposed subjects working for 11 years under these occupational conditions.

Other epidemiological data support that respiratory symptoms are observed at exposure concentrations of V₂O₅that are above 0.1 mg/ V/m³, and are summarized in the following table

Table: Epidemiological studies of V₂O₅ exposure

Subjects	V2O5Dose [mg V /m^3]	Exposure duration	Symptoms	study
24 workers	0.1 - 0.93 mean PS < 5 μm		eye, nose, throat irritation; cough; wheezing, nasal mucosa, rales, rhonchi; injected pharynx and green tongue	Lewis, 1959
2 volunteers	1	8 h	cough, no eosinophilia, normal white blood cell count & cell patterns, no effects on urinalysis, normal lung function	Zenz & Berg, 1967
5 volunteers	0.2 (PS: 98 % < 5 μm)	8 h	loose cough, no eosinophilia, normal white blood cell count & cell patterns, no effects on urinalysis, normal lung function, no detectable V in the blood	Zenz & Berg, 1967
2 volunteers	0.1	8 h	formation of mucus	Zenz & Berg, 1967
3 of 18 workers	> 0.5 mean PS < 5 μm	24 h	inflamed throat, dry cough, burning eyes, no wheeze	Zenz et al. (1962)
11 volunteers	0.4 condensation aerosol		tickling, itching, dryness of mouth mucosa	Pazhynic, 1967
5 of 11 volunteers	0.16		mild signs of irritation	Pazhynic, 1967
11 volunteers	0.08		no notice of symptoms	Pazhynic, 1967
8 volunteers (4 workers + 4 trainees)	0.028 – 0.062	8 h/d, 5 d	no notice of symptoms (i.e. neurobehavioural, neuro-psychological, psychosomatic & psychological effects)	Hörtnagl et al. 1994

 

The Scientific Committee on Occupational Exposure Limit summarized these studies as follows:„In workers exposed to dust containing vanadium (as vanadium pentaoxide) 0.2-0.5 mg/m³for about 11 years, irritants effects on the mucous membranes of the upper respiratory tract were reported. After hygienic improvements, the same workers were exposed to VP concentrations in the range of 0.01-0.04 mg/m³for about 10 months. No worsening of the irritant effects observed as a consequence of the previous exposure was reported for this low-level exposure. In these workers, the exposure did not cause any pathological effects on the blood picture, the cysteine level in the hair, or the respiratory function (Kiviluoto et al., 1979a,b, 1980, 1981a,b; Kiviluoto, 1980)…

Kiviluoto et al (1979a,b, 1980, 1981a,b): in their studies on 63 males exposed in a vanadium factory for 11 years at concentrations in the range of 0.1-3.9 mg/m³(estimated average concentrations 0.2-0.5 mg/m³) and after a further 7-11 month later when concentrations had been reduced to 0.01-0.04 mg/m³studied nasal smears and biopsies. The findings were consistent with irritant effects. Eosinophils did not differ between exposed and non-exposed, nor did IgE-antibody levels. Although exposed workers complained significantly more often of wheezing, pulmonary function tests did not differ. There is, thus, little evidence indicating sensitizing effects on the respiratory tract. The known irritant effects of VP can well explain effects on the respiratory tract including rhinitis, bronchial hyper-reactivity, wheeze, asthma as well as bronchitis…

 

For respiratory tract irritation, and more generally speaking for upper and lower airways effects, dose-response relationships could be obtained in both experimental animals and humans. It can be assumed that 0.04 mg/m3 has to be considered as a NOEL in occupationally exposed subjects (10 months), while in rodents a NOEL could be concluded at an exposure level of 2 mg/m³(B6C3F1 mice, m. f., inhalation, 6h/day, 5d/w for 16 days) and of 1 mg/m3 (F344/N rats, m. f., inhalation, 6h/day, 5d/w for 14 weeks)…

It appears that exposure to concentrations <0.1 mg/m³do not induce irritating effects on the respiratory tract.(SCOEL/SUM/62 Final, January 2004)“

 

Evidence from animal and human data suggests that exposure to elevated V₂O₅concentrations may result in irritating effects on the respiratory system. However, human data were used as point of departure for the DNEL derivation because long-term chronic data are available from workers exposed to vanadium dust using a sensitive indicator of irritation (cytology), a population similar to the target population (workers of the vanadium industry), and to decrease uncertainty for interspecies differences in sensitivity.

The National Toxicology Programme (NTP) in the US nominated tetra- and pentavalent vanadium forms (sodium metavanadate, NaVO₃ (CAS 13718-26-8) and vanadium oxide sulphate, VOSO₄ (CAS 27774-13-6), i.e. species present in drinking water and dietary supplements in 2007 (http://ntp.niehs.nih.gov/). A comprehensive characterisation via the oral route of exposure of

(i) chronic toxicity,

(ii) carcinogenicity, and 

(iii) multi-generation reproductive toxicity

is planned.

 

The NTP testing program began with sub-chronic drinking water and feed studies on VOSO₄ & NaVO₃ as follows:

- Genetic toxicology studies, i.e. the Salmonella gene mutation assays, with NaVO3 and VOSO4 - negative

-14 days with Harlan Sprague-Dawley rats and B6C3F1/N mice (dose: R&M: 0, 125, 250, 500, 1000, 2000 mg/L) - already completed

- 90 days with Harlan Sprague-Dawley rats and B6C3F1/N mice (dose: R&M: : 0, 31.3, 62.5, 125, 250, or 500 ppm) - ongoing

- Perinatal dose-range finding study: gestation day 6 (GD 6) until postnatal day 42 (PND 42) with Harlan Sprague-Dawley rats - ongoing

- 28 days immunotoxicity study (dosed-water) with female B6C3F1/N mice (dose: 0, 31.3, 62.5, 125, 250, or 500 ppm) - ongoing

In addition, repeated-dose inhalation toxicity studies (14, 28, and 90 days) with various vanadium substances are planned within the Vanadium Safety Readiness Safety Program. Further information on these studies can be found in the attachments below. Only upon availability of the results from these studies, it will be possible to render a more meaningful decision on whether or not testing for repeated-dose toxicity is required. Therefore for the time being this data requirement should be waived in consideration of animal welfare.

Justification for classification or non-classification

Currently there is no substance specific data on Vanadate(1-), oxo[phosphato(3-)-κO]-, hydrogen, hydrate (2:2:1) for repeated dose toxicity available. However data from the source compound Divanadyl pyrophosphate (CAS 65232-89-5) as well as tetra- and pentavalent vanadium compounds (e.g. Divanadium pentoxide (CAS 131462 -1)) can be taken into account for hazard assessment.

Based on the available data and according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 Vanadate(1-), oxo[phosphato(3-)-κO]-, hydrogen, hydrate (2:2:1) has to be classified as STOT RE 1 (H372) due to local effects on the respiratory system.